I tried every which way to get this to work, but I don't think it can without some additional code. The ChartModel serialized to OFC via GXT doesn't generate the needed JSON object.

The OFC chart expects the tags to be passed in as an element (ie, treated the same way as a GXT LineChart or PieChart object). So implementing this would be similar to implementing a bar chart overlaid by a line chart - you have to add the bar chart, then create and overlay a "tags" chart (to use OFC lingo). Look at their example at http://teethgrinder.co.uk/open-flash...gs-example.php and view the JSON generated for it for some hints as to the syntax.